In response to the trend of designing lighter, thinner, and smaller products, more and more related techniques for manufacturing miniature-sized device have becoming available. With respect to the overall advance of manufacturing process, both the top-down process and the bottom-up process are focusing on the development of producing nano-scaled devices. However, although the above focusing had led to the generating of many nano-fabrication techniques, most of which are costly and slow to process that they are not suitable to be applied for mass production.
Take the nanoimprint process for instance, it is a mechanical replication technology for the fabrication of micro- and nanostructures that is similar to photolithography or electron beam lithography, except that a mechanical stamp or mold is used to transfer the pattern to the resist. The nanoimprint process has received considerable interest in the last few years because of the successful demonstration of its potential for a low cost, fast, and high resolution nano lithographic technique, so that the nanoimprint technique has been vastly applied in the manufacturing of many nano-scaled devices, such as electronic devices, optical devices, data storage devices, bio-chips, key components of flat panel display, and so on. However, the current nanoimprint process still can not be applied to mass-produce the aforesaid devices since the yield of any product mass-produced by the current nanoimprint process is poor, whereas the poor yield is caused by improper demolding that damages the imprinted microstructures or cause the polymer of the resist to adhere onto the mold. Moreover, the improper demolding may be caused by the high aspect ratio of the pattern to be imprinted, the shrinkage of the resist, the vacuum generated between the mold and the imprinted resist, the factor of friction/viscosity, and so on.
Form the above description, it is known that except for the friction exerting between imprinted microstructures and the affinity exerting between materials used in the nanoimprint process that can cause the mold to be improperly separated from the resist, the vacuum generated between the mold and the imprinted resist during nanoimprint process can also causing the same, whereas the adhesion force of the vacuum effect is far larger than the referring friction and affinity. Therefore, it is concluded that, in order to complete the demolding smoothly, the primary task is to overcome the adhesion force of vacuum effect.
There are already several prior-art techniques known to be able to overcome the adhesion force of vacuum effect. As a demolding method and device disclosed in U.S. Pat. No. 6,416,311 B1, entitled “DEVICE AND METHOD FOR SEPARATING A SHAPED SUBSTRATE FROM A STAMPING TOOL”, the demolding is performed while feeding compressed air through feed ducts formed in the stamping tool so as to overcome the adhesion force of vacuum effect by creating a gap between the stamping tool and the shaped substrate. However, the positioning of the feed ducts on the stamping mold will adversely affect the designs of pattern capable of being formed on the stamping tool, and thus the effective area of the resulting imprinted product is also affected.
Moreover, as disclosed in U.S. Pat. No. 5,358,672, entitled “METHOD FOR DEMOLDING FINISHED ARTICLES FROM GLASS, PLASTIC, OR METALLIC MOLDS”, the demolding can be performed by pulling on the extending portion of a tap adhesively bonded to a mold. However, the pulling of the extending portion of the tap not only can adversely affect the effective area of the resulting imprinted product, but also will quality of imprinted patterns formed adjacent to the tap.
Furthermore, as disclosed in J.P Pat. No. 20040066671, the separating of a mold form a substrate is performed by the use of elastic forces provided by the cooperation of a pneumatic cylinder and a plural sets of spring, whereas the plural sets of spring are abutted against the edge portion of the periphery of the mold. However, the demolding mechanism disclosed above is too complicated to be used for demolding in a nanoimprint process whereas the mold and the substrate are almost of the same size.
In addition, as disclosed in J.P Pat. No. 06270170, the mold is first partially detached from the substrate by the deformation of a shape memory alloy caused by the change of temperature as the shape memory alloy is placed against the edge of the mold, and then the mold is separated completely from the substrate as the substrate is restrained by a block as the mold is being lifted to move away from the substrate. However, the demolding requires a specific shape memory alloy designed to cope with the temperature change in the imprinting process, and it also requires a proper block to restrain the substrate, because of which the imprint process is complicated.
From the above description, it is noted that most prior-art demolding methods use a certain means to exert force upon the edge of either the mold or the substrate, which may require uncommon material or complex mechanism for the demolding to be operated smoothly. Moreover, the disposition of those complicated demolding devices usually will cause damage to the effective area of the imprinting and quality thereof.